This invention relates to a data transfer speed control apparatus capable of varying speed data transfer speed between two devices, depending on the data transfer speeds of the two devices, and in particular to a data transfer speed control apparatus, which is suitable for the data transfer between devices the data transfer speeds of which are different or can be arbitrarily set, e.g. between a semiconductor storage device, such as an IC disc, etc., and a device of higher rank therefor.
As prior art techniques for mutually transferring data between two devices having different data sending/receiving speeds are known those disclosed by, for example "IBM 3380 Storage Control Models 1, 2, 3 and 4 Description Manual" (published 1985) p. 5-15 "Speed Matching Buffer for 3380", p. 5-14 "Speed Matching Buffer for 3375". According to these prior art techniques, e.g. in the case where data are mutually transferred between a channel device and a disc device, the difference in the data transfer speed between the channel device and the disc device is absorbed by disposing a large capacity data buffer within a control device controlling the disc device and by temporarily storing the data transferred between the channel device and the disc device in this data buffer.